Multiway telegraph repeater system



Dec. 29, 1953 F. H. HANLEY MULTIWAY TELEGRAPH REPEATER SYSTEM 2Sheets-Sheet 1 Filed Jan. 26, 1950 lNl/ENTOR I: H. HANLEV ATTORNEY FiledJan. 26, 1950 Dec. 29, 1953 F. H. HANLEY 2,664,466

MULTIWAY TELEGRAPH REPEATER SYSTEM 2 Sheets-Sheet z I I-l l l l FIG. 2

ATTORNEY Patented Dec. 29, 1953 UNITED S'iAl'rES PATENT QEHQE MULTIWAYTELEGRAPH REPEATER SYSTEM Application January 26, 1950, Serial No.140,707

13 Claims.

This invention relates to telegraph systems and particularly to multiwaytele' raph repeaters arranged for hub operation. The hub circuitoperation enables additional repeater circuits to be established, or theexisting circuit to be rear ranged, without loop-poling changes, adustment of loop currents, whereby it becomes unnecessary to compensatefor added or removed loop or line circuits.

An object of the invention is to simplify the operat on of repeatersarranged for hub circuit operation by arranging all repeaters of thesystem for full duplex operation regardless of whether single, one-wayor full duplex service is to be furnished, and reducing, in general, theamount of equipment required for satisfactory repeater transmission.

Eeretofore multiway telegra h repeaters arran ed for hub operationrequired a relatively high current or o erating the send relay of eachof the repeaters of a repeater system, whereby the number of repeatersin a telegraph concentration group wa limited.

According to the present invention a considerably large number of loopand line circuits may be arranged for interconnection at a repeaterstation. Each of the loop or line circuits has a receive and a send leor conductor. Each receive conductor terminates in the operating windingof a receive relay and each send conductor terminates at the armature ofa send relay. The receive relay is normally held in its marking positionby the current normally flowing in its operating winding, the biasingcurrent in the other winding, when used, or a mechanical bias on thearmature, or the like being effective to operate the relay to itsspacing position when its loop or line circuit is opened. The send relayis normally held in its marking position by current flowing in a markingdirection through its two windings connected in series aiding, and isarranged to operate to its spacing position in response to a currentflowing in a spacing direction through its two windings, in seriesaiding. interconnecting the hub sides of the receive and send conductorsof each repeater are means ooerable in response to the signals incomingover the receive eg of a loop or line circuit, to hold the associatedsend relay in a marking position for the duration of the messageincoming over the receive conductor and thereafter until a mesisreceived over the receive conductor of another loop or line circuit. Inone arrangement the interconnecting mean responsive to signals incomingover the receive conductor is an electrou magnetic relay arranged tooperate in response to the start impulse of the first code combinationof the incoming message and to remain operated for the duration of themessage and thereafter until the signals are received over the receiveconductor of another loop or line circuit of the repeater system. In analternative arrangement the electromagnetic relay serving as theinterconnecting means is replaced by an impedance network comprisingresistors, an inductance and an electronic tube which, under similarcircumstances, maintains the send relay associated with the loop or linecircuit over which signals are be ng received at the time in a markingposition for the duration and thereafter until signals are received overthe receive conductor of another loop or line circuit.

A feature of the present invention resides in the provision of meansinterconnecting the drop or hub side of the receive and send legs ofeach repeater in the repeater system for preventing the operation of thesend relay during the time when its associated receive relay isreceiving signals incoming over its loop or line circuit.

Another feature is the provision of an impedance network comprisingresistors, an inductance and an electronic tube interconnecting the dropor hub side of the receive and send legs of each repeater in a repeatersystem for preventing the operation of the send relay during the timewhen its associated receive relay is receiving signals incoming over itsloop or line circuit.

Another feature pertains to the use of the three relays whereof oneserves as a control relay interconnecting the hub side of the receiveand send conductors of each repeater in a multiway regenerative repeatersystem for preventing the operation of the send relay during the timewhen its associated receive relay is receiving signals incoming over itsloop or line circuit, and immediately thereafter until the regenerativerepeater returns to its normal marking position.

Another feature is the elimination of the apex battery tap from thewindings of the send relay of a repeater whereby a current of 5milliamperes in the two windings, in series aiding, of the send relay ofeach repeater provides as much margin in operation as a current of 20inilliamperes in one winding with a biasing current of 10 milliamperesin the other to permit the operation of four times as many leg inparallel with a given current flow. For example, a current of 100milliamperes flowing through the contacts of the hub relay would permitfive legs at 20 milliam- V pores of current to be operated in paralleland legs at 5 milliarnperes of o erated in parallel.

the provision of an elec receive conductor of each of the 1003 and linerepeaters for preventing the shunti of the repeater common to all theloop and line repeaters of the multiway repeater systern.

Another feature resid s in the rovisi n of an arran ement wherein a lare num er of lo p and line circuits be interc nnected directly throu h asim le repea r or throu h a One-way re enerative repeater without comingsignal torticn or reducing th speed of operation,

Another feature r si in the standerv t on f the, app arance nf all loopnd line circuits nf gre tly different ch antovish'cs at a r ter stationso 2s t fac l t te th r interc nnect on to add. other l p and line crcuits or to r ace 03. remove exist ng Icon mlifln niv'mfiiig wit-hard;adiustment or compen at n of ist nce v ]"S Other obi p s and, featurwill a p ar in the, followin deta led descri t n and ns m cla ms wh ncon red w th r ference to the accompan ing drawin s n wh ch:

shows a, snhemnfin c rcu t, qr'v nc'nm nt Of a, KQl'rfwav ,te'lnnronhrnn mi 'r svqtnm nnmnvis no a plur l t of lo p a d line nwt i'ntm'-,nneoted for nub nneistinn each hav ng thvnrq lericd electro tic r s. nv, a rece ve relay. end rela an a c nt l r av ogper t 'nq with commonvonnut m w-s h control rela in its finer-2119 pos t n p evi w-S its sendrel fro r t n the sa over th loop or ne c rcuit fr which Hi r n' gnn worigina ly rec ved: F 1 A shows th W rng recuir l for F 1 wh n the ren tv'rel-av n pants: the s nal irwnm hrr n moo I n ml ng circuit directl tot e send r ays or the rema nin lo and l ne circ -ts: Fi l-R s w s emetrially a re enerative r a er and ringtherefor. used w th th system shownin F g 1, The use of the contr l relav m ke p ferable the of the reenerat e repeater: and

3. 1 2 shows an alternative s stem for th t shown in Fi 1 wherein th c nrol ay c cuit for each repeater s eliminated. The number or huhconductors is re uced from th ee to two the use of. an electronic tubein the r ce ve le of each repeater p rm ts an number of ph le s to beconnected to ether t f rm a circuit without havin any shunt ng e ect onthe operating winding of the hub rela and becau e of the eli ination ofthis shunt n effect. the alternat ve system. does not. neces itate rpetiby means of a reoenera tive repeat r although the use of suchrepeater may be desirable.

The electronic tube may be a so used in the shown in Fig. 1 to producethe same would permit twenty cu rent n each to be [mo feature is tropictube in the though the loop and line circuits are for difnt uses withrespect to their apoli cation to the the terms loop. line, loop circuitl ne circuit will. for patent purposes, be d herein interchangeably.

General description of Fig. 1

, circu t over which incoming signals are received in an operatedposition for the duration of the incoming message and. thereafter untila message begins to come in over another loop or line circuit. Thissystem employs three hub conductors, namely, a receive hub, a send huband a control uh, each of which is common to the loop and. line c rcuitrepeaters employed in the system. The control electromagnetic relay isor" the polariced type and operates in response to the first or startimpulse of a me sage incomins over the receive leg of a loop or linecircuit. This control relay remains locked operated until the directionof message transmiss on over such loop or line cicuit is reversed. Aregenerative repeater for furnishing regenerated signals for tran mision to the loop and line circuits other than the one from which theincoming messa e is received, may be ies'ra'cle when a control relay isused in each of the'locp and line repeaters. because, as hereinbeforestated, the third hub conductor necessitated by the use of a controlrelay has a shunt ing effect on the winding of the hub repeater relay.

During the idle periods the receive relay of the repeaters are in theirmarking or right-hand positions and no current flows through theoperating or upper w ndings of any of the control relays. Each controlrelay comprises, in addition to its operating winding. 2. hold winding.When no current i flowing in the operating winding of a control relay,current is fiowng in the hold winding thereof in a direction to hold therelay armature locked in the position to which it was last operated.This current flowing through the hold winding when the relay is in tsmarking position is a net ouantity resulting from currentssimultaneously flowing from two oppositely poled sources through thewinding as will be hereinafter described. When incoming signals arereceived over any of the loop or line circuits they are repeated notonly over the receive conductor of such loop or line repeater to acommon repeater but also over the common control hub circut whichextends through the operating windings, in parallel, of all the controlrelays. In response to the first or start impulse of a message, acurrent flows in a spacing direction, that from left to right throughthe operating winding of the control relay associated with the loop orline c rcuit over which the incoming message is being received, and in amarl:- ing direction, that is, from right to left through the operatingwinding of each of the control relays associated with the other or idleloop and l ne circuits. Accordingly, the control relay associated withthe loop or line circuit over which the message is received operates toits spacing or left-hand position as shown at relay l-C-Z whereby thesend relay associated with the same loop or line circuit is held lockedoperated in its marking or right-hand position as shown at relay l-S-Zfor the duration of the message incoming over such loop or line circuitand there after until the direction of message transmiss on over suchloop or line circuit is reverse When the send relay is held in itsmarking position by its associated control relay being held in itslefthand position, the signals in the output circuit of the commonrepeater are prevented from being transmitted over the send leg of theloop or line circuit over which the incoming message is re eived andtherefore no message can be repeated hack to the station or distantpoint at which it originated. The control relays respectively a=-sociated with the idle loop or line c rcuits are at this time operatedto or maintained in their marking or right-hand positions as shown atrelays i-C-l and l-C-IU, and therefore the send relays respectivelyassociated with these idle l ne and loop circuits are free to respond tothe output of the common repeater whereby the message is repeated byeach of such send relays over the send legs of the idle loop and linecircuits.

It will be observed in the system shown in Fig. 1. that relays i-R-i,l-S-i and l-C-I are as ociated with loop circuit till-A; relays i-R-Z,l-S-Z and I-C Z are associated with loop circuit lQl-B and relaysi-R-ld, i-S-it and l-C-ifl are associated with line circuit iiSi-J. Thel-R relays are the receive relays responsive to signals incoming overtheir respective rece ve legs of the loop or line circuits. The l-Srelays are the send relays and are provided to send signals from thesend hub circuit conductor i-SH to the send legs of their respectiveloop or line circuits over which no signals are incoming at the timewhen the rece ve leg of another loop orline circuit is receivingsignals. The i-C relays are the control relays which, upon receiving thefirst start impulse of a message incoming over their respect ve loop andline circuits, control the operation of their respective send relays.

The receive relay rece ves the signal impulses over its receive leg andrepeats them in parallel paths extending (1) over receive hub conductorl-RH and through the opera ing or upper winding of hub relay l-H, and(2) through the upper winding of its control relay and then through theupper windings, in parallel, of the control relays respectivelyassociated with the other loop or line circuits.

The improved multiway repeater may use hub relay E-I-l only, which is ofthe simple repeater type, for repeat ng the signals incoming over oneloop or line circuit to each of the other loop or line circuits and insuch case the output circuit of relay l-I-I extends in a manner as shownin Fig. l-A. In multiway repeater systems wherein regenerated signalsare required, the output cir cult of relay I-H'may extend as shown inFig. 1-13. In Fig. l-B, relay 2-H represents a oneway regenerativerepeater which may he of the type shown and described in Patent2,105,173 granted to W. J. Zenner on January 11, 1938,

which patent is hereby made a part of this specification as if fully setforth herein.

In the regenerative repeater the signals are restored to their properlength, as originally transmtted, by an electromechanical timingmechanism well known in the art. The changing of the signals back totheir original length, as transmitted from the distant end of a loop orline circuit, involves storing the received signal elements in theregenerating mechansm for a short interval equal to about half thelength of each element, while the nature of each character formingelement is definitely determined. Then each element is retransmitted bywhat may be generally characterized as a motor driven electromechanicalinterrupter which transmits signal elements of proper length. Theretimed s'gnals are then transmitted simultaneously to send re laysrespectively connected to the loop and line circuits other than the loopor the line circuit over which the signals were received and these sendrelays simultaneously repeat the retimed signals to their respectivelyassociated loops and line circuits.

Detailed description of Fig. I

In the arrangement shown in Fig. l, the effect of current flowingthrough the windings of the three relays of a line repeater will firstbe explained. Relays l-R-2, i-S-Z and l-C-Z of the repeater of loop crcuit till-B will be used to illustrate this operation and will sufiicefor the repeaters of the other loop and line circuits such as circuits"FL-A and till-J. Circuits Elli-A, ifil-B and iEH-J are representativeof ten or more loop and line circuits.

If it should be assumed that station E was not the last station of thesystem to transmit a message to the multiway repeater, the repeater andcontrol circuits of line circuit iiii-B would, during the idle periods,extend from grounded negative IBG-volt battery connected to the markingor right-hand contact M and armature of re ceive relay i-R-Z to twoparallel paths, the repeater circuit including resistor i334; having aresistance value, say of 18,660 ohms, receive huh conductor l-RH, theupper winding of relay i-H to grounded negative T ll-volt battery, andthe control circuit including resistor tilt-l3 having a resistancevalue,-say of 3,006 ohms, upper winding of relay I-C-2, controlconductor i-C, to which the upper windings of the other control relays,such as i-C-i and i-C-it are connected, the upper windings ofthese'othcr control relays being connected to paths respectivelyextending through resistors, such as resistors EM-A and iil i-J, togrounded negative LEO-volt batteries connected at the marking contacts Mand armatures of receive relays i-R-i and i-Rait, respectively. Each ofthe other resistors, such as resistors ifl4-A and. Elle-J, also has aresistance value say of 3,000 ohms. It will be noted that the receivehub conductor i-RH is also connected to loop circuit lfli-A in a pathincluding resistor ids-A, the armature and marking contact M of receiverelay l-Rr-i and grounded negative 13% volt battery, and for linecircuit H254, to a path including resistor iiiB-J, the armature andmarking contact M of receive relay L348 and grounded negative mil-voltbattery. Each of the resistors, such as resistors ills-A and @3J, has aresistance value of 13,090 ohms like eat of resistor HIS-B.

As hereinbefore stated, during the idle periods of the multiway repeaterwhen no current is ilow ing in the operating or upper winding of acontrol relay, current is flowing in the hold or lower winding thereofin a direction to hold the relay armature locked in the position towhich it was last operated. In the control relays associated with theloop or line circuits which are receiving signals from the commonrepeater, the current in the hold winding of each of these relays is ina marking direction. Relays iC-i and i-C- i: are shown with theirrespective armatures in engagement with their marking contacts M, aposition in which they are loczed during the time when they arereceiving signals from the common repeater and thereafter until amessage is re ceived over their respective line or loop circuit. It willbe noted that the armature of relay i-C--2 is shown in its spacingposition. The armature of a control relay associated with a or loopcircuit over which incoming signals werelast received remains in itsspacing position until signals are received from another loop. or linecircuit.

It will now be assumed that stat-ion associated with control relay i-C-2has sending and another station, such as station A, starts to send.Accordingly, control relay i-C-l which is associated with the linecircuit about to send is, as hereinbefore stated, in its mark ng g timethe current will again flow in the operating or upper winding of relayl-C-i but in the opposite direction whereby relay l-C-I operates itsarmature back to its right-hand position in which it is locked for suchother message.

Description of the ystem shown in Fig. 2

The system shown in Fig. 2 diiiers from that shown in Fig. 1 in thateach loop or line circuit has instead of a control electromagnetic relaya control network comprising an inductance coil, resistors and anelectronic tube preferably of the ordinary two-element neon type. Itcoinprises for each line or loop repeater (l) a receive relay which uponresponding to signals incoming over its loop or line circuit repeats theincoming signals as polar impulses on an inverse neutral transmissionbasis over an output circuit whereof a conductor extends in seriesconnection through a resistor having a resistance value, say of 9,501;ohms, a gaseous type of electric discharge device designed to ionize atabout 70 volts, the operating winding of a hub electromagnetic relay toa source of grounded negative potential, say of 130 volts; (2) 2. sendrelay for retransmitting over the send leg of its loop or line circuitsignals repeated by the hub relay from a source of potential, say of 130volts, the signals being repeated over a circuit path ex tending througha resistor having a resistance value, say of 26,000 ohms, the windingsin series aiding of the send relay to ground; and (3) theabove-mentioned control network whereof its inductance coil is connectedto the receive relay output conductor and its resistor is connected tothe send relay input conductor at points respectively adjacent to thearmature of the receive relay and the operating or upper winding on thehub side of the send relay. The control network resistor has aresistance value, say of 13,000 ohms. Also each loop and line repeaterincludes a second resistor having a resistance value of the order of13,060 ohms connected to a source of grounded positive potential, thelatter resistor being connected to the send relay input conductor at thesame point as the control network resistor of the same resistance valueof 13,068 ohms. The control network controls its send relay whereby thesend relay of the repeater associated with the loop or line circuit overwhich the message signals are incoming is held in its marking orright-hand position for the duration of the incoming message andthereafter until a message is received from another of the loop or linecircuits. Only two hub conductors common to all the loop and linerepeaters of the system are required.

The use of the tube in the receiving relay output circuit of a loop orline repeater permits any number of, such output circuits to beconnected together to form a repeater system without having any shuntingeffect on the operating winding of the hub relay as exists in the systemshown in Fig. 1 wherein the current flowing in the control conductor ofany one of the loop or line repeaters also flows in the controlconductors of all the other loop and line repeaters of the system inshunt to the operating or upper winding of the hub relay therein.

It will be noted in the system shown in Fig. 2 that associatedindividually with each of the subscriber loop circuits 2ili-A, Mil-B,etc. and each of the line circuits, such as line circuit EDI-J, are tworelays only, such as relays Z-R-i and 2-3-1, which are associated withthe loop iii circuit ZM-A and relays Z-R-It and 2-345 associated withline circuit ZEN-J. The Z-R relays are the receive relays responsive tosignals incoming over their respective receive legs of the loop and linecircuits, for example, relay E-R-i is responsive to signals incomingover receive leg Z-RL-A of loop circuit Ztl-A. The 2-8 relays are thesend relays and are provided to send signals from the send hub circuitconductor 2-SH to the send legs of these loop and line circuits whichare idle at the time when message signals are incoming over one of theloop or line circuits, for example, should. message signals be incomingover the receive leg Z-RL-A of loop circuit Ziii-A then these would berepeated by hub relay 2-H to the send relays of the other loop and linecircuits, such as relays 2-5-2 and E-S-l c, which would repeat thesignals for transmission over their'respective send legs Z-SL-B andZ-SL-J of the loop circuit 288-13 and line circuit Zili-J.

In the output circuit conductor of the receive relay of each loop andline repeater are a resistor and a gaseous type of electric dischargedevice, such as resistor 283-A and tube Z-T-i, respectively, for therepeater of loop circuit Edi-A. In the input circuit conductor of thesend relay of each loop and line repeater is a resistor such as resistor2fl5-A in the repeater for loop circuit Edi-A. The receive relay outputcircuit conductors of all the loop and line repeaters of the system areconnected in parallel to a receive hub Z-RH which forms a part of theinput circuit of hub relay 2-H. The send relay input circuit conductorsof all the loop and line repeaters are connected in parallel to a sendhub Z-SH which forms a part of the output circuit of hub relay 2-H.interconnecting the output circuit conductor of the receive relay andthe input circuit conductor of the send relay of each of the loop andline circuit repeaters is the control network which comprises theinductance coil and the resistor connected in series in a manner asrepresented by the arrangement of coil Zol-A.

- and resistor Zfld-A in the repeater for loop circuit fill-A. The coilZill-A is connected to the output conductor of receive relay 2-..v-fi ata point adjacent to the relay armature, and the resistor Edi-A isconnected to the input conductor of send relay Z-S-l at a point adjacentto the hub side of the upper Winding of the send relay. Also connectedto the send relay input circuit conductor at a point adjacent to the hubside of the operating winding of the send relay of each loop and linerepeater is a resistor connected to a source of grounded positivepotential, say of 130 volts, the resistor being such as that designatedZMi-A for the repeater on loop circuit ZtI-A.

The receive relay of each repeater is arranged to receive the signalimpulses incoming over its receive leg and repeat them through itsassociated electric discharge tube to the operating or upper winding ofthe hub relay 2-H. I-lub relay 2-H operates in a manner substantiallysimilar to that of the hub relay l-H in Fig. 1. Hub relay 2-H. has abiasing or lower winding connected to a source of grounded negativepotential, say of 130 volts, whereby a marking current, say ofapproximately 10 milliamperes, nor-- mally holds the relay in itsmarking or righthand position. In each of the loop and line repeatersthe value of the resistance of the resistor such as resistor EOE-A ofthe repeater of loop circuit fill-A is, say 9,500 ohms, which is suiniicient to produce a spacing current of approximately 20 milliamperes inthe operating or upper winding of hub relay 2-H at a time when a spacingsignal impulse is received from the loop or line circuit. Under thiscondition since the potential difierence across the tubes in the receiverelay output circuit conductors of those repeaters which are inreceiving position at the time is considerably less than 70 volts whichis the potential required to ionize the tube, no current will flow inthe receive leg of the idle repeaters and consequently the operatingwinding of hub relay 2-H will not be shunted. With this arrangement, noshunting efiect will occur regardless of the number of repeatersemployed in the multiway repeater system.

The send relay or" the repeater associated with the loop or linerepeater over which message signals are being received is held operatedto its marking or right-hand position for the duration of the messageand thereafter until the direction of transmission over such loop orline circuit is reversed by means of the resistor interconnecting theoutput circuit conductor of its receive relay and the input circuitconductor of the associated send relay.

Detailed description of system in Fig. 2

The operation of the multiway repeater system shown in Fig. 2 will nowbe described in detail. When the system is in normal condition, thearmatures or" receive relays Z-R are on their respective markingcontacts. Under this condition, the control network of each repeaterreceives a iii-milliampere spacing current from a source of negativepotential, say of 130 volts, connected to the marking contact of itsreceive Resistance of tube 2T1=R= 130 volts 48L00 relay. In the case ofreceive relay 2-R-i, this spacing current flows through resistor Zed-Ahaving a resistance value of 13,000 ohms, and the windings in seriesaiding of send relay Z-S-i. Also in the case of receive relay Z-R-l, a-"nilliampere marking current flows at the same time from a source ofpositive potential, say of 130 volts, through resistor Bibi-A having aresistance value of 13,000 ohms, through the windings in series aidingof send relay fZ-S-l to ground. I'hese 10-milliampere currents flowingin opposite directions throu gh the windings of send relay 2-8-1neutralize each other and therefore have no effect on send relay Z-S-I.However, there is a marking current of 5 milliamperes simultaneouslyflowing from a source of positive potential, say of 130 volts, on themarking contact of hub relay 2-H, through resistor zilfi-A of aresistance value of say 26,000 ohms, the windings in series 130 volts atM contact on relay 2H start impulse of the first incoming signal whichimpulse is always spacing, the armature of receive relay Z-R-i moves toits spacing contact. While the armature is traveling between contacts,

that is, from its marking to its spacing contact,

the normal current flow in the winding of send relay Z-S-l is increasedfrom 5 milliamperes in the marking direction to 12.3 milliamperes in themarking direction by the difference in the marking current flow of 15milliamperes and a spacing current flow of 2.7 milliamperes. The15-milliampere current flows from two parallel paths one being traceablefrom the source of positive potential of 130 volts at the markingcontact and armature of hub relay 2-H, send hub conductor 2-SH, resistor205-A of 26,000 ohms resistance, through the winding in series aiding ofsend relay Z-S-l to ground and the other being traceable from the sourceof positive potential of 130 volts through resistor 20E-A of 13,000 ohmsresistance and the windings in series aiding of send relay 2-i-S toground. The 2.7 inilliamperes current in a spacing direction is producedin a circuit traceable from a source of negative potential of 130 voltsconnected to the winding of hub relay 2-H, through the relay winding,receive hub conductor Z-RH, tube Z-T-l, resistor 203-A of a resistancevalue of say 9,500 ohms, inductance coil EDI-A, resistor ZM-A of 13,000ohms resistance, the windings, in series aiding, of send relay Z-S-i, toground. The resistance of tube Z-T-l for this interval of the traveltime of the armature of relay Z-R-i is equal to 26,000 ohms, the totaleffective resistance for the circuit producing the 2.7 milliamperescurrent being 26,000 ohms, plus 0,500 ohms, plus 13,000 ohms whichequals 48,500 ohms.

=26000 ohms =2.7 milliamperes spacing current When receive relay Z-R-lreaches its spacing contact and before hub relay 2-H leaves its markingcontact, a marking current of approximately 25 milliarnperes flowsthrough the windings, in series aiding, of send relay Z-S-i. In thiscase where two parallel resistors Zilt-A and 205-0. are equal in theirresistance value, say 13,000 ohms eac the current thus flowing throughthe windings, in series aiding, of send relay 2-3-1 when the armature ofrelay Z-R-l reaches its spacing contact before the armature of hub relay2-H leaves its marking contact is 10000 ohms 2 13000 ohms =+25milliampheres, marking current X 26000 ohms +26000 ohms When thearmature of hub relay 2-H is positioned in engagement with its spacingcontact, the marking current in the winding of send relay 2-S-l isreduced to fifteen milliarnperes, that is, the difference between twentymilliamperes marking current and five milliamperes spacing current.

When a marking signal is again received the armature of relay Z-R-l ispositioned to its mark- I milliamperes, spacing current ing contact.During the time when the armature +l30 volts 1- Ohmsmilllamperes,marking current 1Q volts 130 volts spacing current in the operating orupper winding of hub relay 2-H to collapse quickly.

130 volts I 6500 oh +29 p s, marking current Transmission from hub relayto send relay of repeaters in sending condition When a repeater is in asending condition, that is, with its receiving relay armature inengagement with its marking contact, the current flow from the source ofnegative potential, say Of 130 volts, through a resistor such asresistor res-e of 13,000 ohms, is neutralized by the current fiovv fromthe source of positive potential of 130 volts, through the resistor205-13 so that the combined effect of these currents on the winding, inseries 26100 ohmsX 13000 ohms+9500 ohms+26000 ohms) spacmg Trent 20000ol1ms-l-48000 ohms Should the armature of relay 2-R-l reach its markingcontact before the armature of relay 2-H leaves its spacing contact, aspacing current of approximately 5 milliamperes (spacing) would flowmomentarily through the windings, in series aiding, of relay Z-S-l.

130 volts 26000 ohms In order to prevent the tendency of kick-off =5milliamperes, spacing current.

by the send relay armature in the case where the send relay is of highsensitivity, an inductance such as inductance 20'l-A, and a tube such astube 2-T-l, are used in series with their associated resistor such asresistor Zll l-A. However,

should the inductance and the tube be omitted 5-.

in each of the repeater circuits, the tendency of the send relay tokick-off its contact when the associated receive relay is receiving isnoticeable only by a click sound in a telephone headset when one is usedfor testing purposes, but this tendency is insumcient to causedistortion to be recorded in the transmission measuring set in any partor the loop or line repeater circuit.

Elimination of the tendency for the kick-off effect by the inductanceand the tube is due to the hub relay 2-H causing its armature to operatemore rapidly from its space to its mark position with the inductance andtube, than without them and because the build-up of the current causedby the closure of the armature aiding, of send relay 2-S-2 is zero, andconsequently an eiiective current of approximately five milliamperesfrom the source of either negative or positive potential of volts on thearmature of hub relay 2-H, through resistor 205-13 of 26,000 ohms,through the windings, in series aiding, of send relay 2-S-2 to ground,cause relay 2-S-2 as well as the send relays of the other idle repeatersto follow the signals repeated by hub relay 2-H.

The use of an electronic tube in the receive conductor of each of theloop and line repeaters is not restricted to gas tubes, but may beserved by vacuum tubes as well.

The quantities used herein are for illustrative purposes only and may bevaried, as desired, to produce results that are within the scope of theinvention.

What is claimed is:

1. A telegraph system comprising a plurality of lines, a line repeaterhaving a receive and a send relay for each of said lines, an output circuit for each of said receive relays, a common repeater connected to thereceive and the send relay of each of saidv line repeaters, meanscontrolled by the first or start impulse of a message incoming over anyone of said lines and repeated by the receive relay thereof forpermitting the message repeated by said common repeater to beretransmitted by the respective send relays of the line repeaters of theother said lines only, and other means connected in each of said outputcircuits for preventing the shunting of said common repeater during thereception of a message by the receive relay of any one or said linerepeaters.

2. A telegraph system, according to claim 1, wherein said other meansincludes an electronic device for regulating the amount of currentflowing through each of said output circuits to said common repeater.

estates iii 3. A telegraph system, according to claim 1 wherein saidother means includes a gaseous electronic tube for regulating the amountof cur rent flowing through each or said output circuits to said commonrepeater.

4. A telegraph system comprising a plurality of lines, a line repeaterhaving a receive relay, a send relay and one control relay only for eachof said lines, a common repeater connected to the r ceive and the sendrelays of said line repeaters, and circuit means controlled by saidcontrol relay or any one or" said line repeaters in response to thefirst or start impulse of a message incoming over the line associatedwith said one r maintaining operated the send relay iter for theduration of the cssage repeated by said common reeaiter until anothermessage is received over another one of said line repeaters.

5. A telegraph system comprising a plurality of lines, a repeater havinga receive and a send relay connected to each or said lines, a commonrepeater, a receive conductor connecting each of said receive relayswith said common repeater, a send conductor connecting said commonrepeater with each of said send relays, and circuit meansinterconnecting the receive and send conductors or each or said linerepeaters, impedance means included in each of said circuit meanseffective in response to the first or start impulse of a messagereceived over its line and repeated by the receive relay or its linerepeater to said common repeater to thereby hold the send relay of itsassociated line repeater non-responsive to the signals of the messagerepeated by said common repeater and thereafter until another message isreceived over another of said lines.

6. telegraph system comprising a plurality of lines, repeater having areceive and a send relay connected to each of said lines, a singleone-way repeater for repeating message signals received from receiverelay or" any one of said line re atcrs to the send relays of all theother line repeaters, circuit means interconthe receive the send relayor each impede; e means included in said cans effective in response tothe first or star a message received from the receive relay of any oneof said line repeaters for preventing the send relay of said one linerepeater from transmitting the message repeated by said single oneavayrepeater to the line over which it received.

A telegraph system comprising a plurality of lines, repeater having areceive and a send relay connected to of said lines, a common repeater,receive conductor connecting each of said receive relays with saidcommon repeater, a send conductor connecting said common repeater witheach oi said send relays, an impedance network interconnecting thereceive and send conductors of each said line repeaters, and a secondimpedance n twork and a grounded potential source cooperating therewithior holding in locked condition in response to the first or tart ulse ofa message repeated from any one or" said lines, the send relay of saidone line to thereby prevent the message repeated by said common repeaterfrom being transmitted back over said one line.

8. A start-stop telegraph system comprising a plurality of lines, arepeater in each line having a receive and a send conductor, a circuitinterconnecting said conductors of each repeater. op eracle means ineach receive conductor responsive to start-stop signals incoming overits line, a source of polar signals, a pair of contacts in engageablerelation with each or said operable means for impressing space and markcurrent impulses from said source on the receive conductor of itsassociated line repeater for repetition over the send conductors of theother repeaters only, a source of potential connected to each of saidinterconnecting circuits, means in one or said circuits controlled byits associated one of said operable means and eiiective in response to aspace current impulse-from said source of polar signals for causing onecircuit to be energized from its source of potential in such a manher asto maize the send conductor of said associated line repeater ineffectivefor the duration oi the message and thereafter until an incoming signalis, received over another of said lines, and other means in the other ofsaid circuits con trolled by the other of said operable means formaintaining their respectively associated interconnecting circuitsdeenergiz-ed in such a manner as to make the send conductors of saidother repeaters effective to repeat the signals for outgoingtransmission over their respective lines.

9. A start-stop telegraph system comprising a plurality of lines, arepeater having a receive and a send relay connected to each of saidlines, a common repeater, a receive conductor connecting each of saidreceive relays to said common repeater, a send conductor connecting saidcommon repeater to each of said send relays, in parallel, a controlrelay inter-connecting the receive and send conductors of each of saidline repeaters, each control relay having means re sponslve to the firstor start impulse of a message received over its line and repeated by thereceive relay of its line repeater to said common repeater, to hold theS6110. relay of said line repeater non-responsive to the signals of themessage and thereafter until another message is received over another ofsaid lines.

10. A start-stop telegraph system comprising a plurality of lines,operable means for each line responsive to start-stop signals incomingover its line, a relay for each line, said relay having an operatingwinning. a hold Winding, an armature and contacts in engageable relationwith said armature, a source of polar signals, a pair of contacts inengageable relation with each of said operable means for impressingspace and mark current impulses from said source on the operatingwinding of said relay, a source of potential connected to the holdwinding of each of said relays, circuit means controlled by each of saidoperable means and effective in response to a space current impulse fromsaid source of polar signals for operating the armature of the relayassociated with the line over which the incoming start-stop signal isreceived, to its associate alternate contact and for maintaining thearmature of the relays associated with th other of said lines at theirrespective normal contacts, other circuit means including the holdWinding of each of said relays for holding its relay armature incontinuous engagement with its respective alternate or normal contactfor the duration of a message and thereafter until a signal is receivedover another of said lines.

11. A telegraph signal comprising a plurality of lines, a repeater foreach of said lines, a com mon repeater, a receive conductor connectingeach of said line repeaters to said common repeater, 2. send conductorconnecting said common repeater to each of said linerepeaters, a

control relay for interconnecting said receive and said send conductorof any one of said line repeaters, operable means and a pair of contactstherefor on said control relay, a hold winding on said one control relayfor holding said perable means in engagement with either of the contactsof said pair, means controlled by said operable means when held inengagement with one of said contacts for maintaining said one linerepeater non-responsive to signals repeated by said common repeater inresponse to signals incoming over said one line repeater, and othermeans controlled by said operable means when held in engagement with theother of said contacts for maintaining said one line repeater responsiveto signals repeated by said common repeater in response to signalsincoming over another of said line repeaters.

12. A telegraph system comprising a plurality of lines, a repeater foreach of said lines, a receive, a send and a control relay in each ofsaid line repeaters, a common repeater for retransmitting incomingsignals received from the receive relay of any one of said linerepeaters to the send relays of all the other of said line repeaters,said control relay having an operating winding for receiving signalsfrom the receive relay of any one of said line repeaters, and anarmature and a pair of contacts therefor, a hold winding on each of saidcontrol relays for retaining said armature in engagement with eithercontact of said pair depending on which one of said receive relays isreceiving signals from its line, means including said armature inengagement with one contact of said pair for preventing the send relayassociated with the receive relay receiving signals from its line fromresponding to the signals transmitted by said common repeater, and othermeans including said armature in engagement with the other contact ofsaid pair for preparing the send relays respectively associated with thereceive relays of the idle lines to respond to the signals trans mittedfrom the common repeater.

13. A telegraph system comprising a plurality of lines, a line repeaterhaving a receive relay and a send relay for each of said lines, a commonrepeater connected to the receive and send relays of said linerepeaters, circuit means interconnecting the receive relay and the sendrelay of each of said line repeaters, and means included in each of saidcircuit means and responsive to the first, or start, impulse of anincoming message signal repeatered by the receive relay of therespectively associated line repeater for preventing the send relay ofsaid respectively associated line repeater from responding to impulsesrepeatered by said common repeater.

FRANK HAROLD HANLEY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,069,223 Cummings Feb. 2, 1937 2,154,624 Kinkead Apr. 18,1939 2,334,551 Hanley Nov. 16, 1943 2,539,550 Rea Jan. 30, 19512,539,551 Rea Jan. 30, 1951

